Carpal tunnel syndrome (CTS) is a condition characterized by numbness, tingling, weakness, and other symptoms in the hand and wrist area. These symptoms occur due to compression of the median nerve as it travels through the carpal tunnel, a narrow passageway in the wrist formed by bones and ligaments. The median nerve provides sensation to the thumb, index finger, middle finger, and half of the ring finger, as well as controlling certain muscles in the hand.